1. Field of the Invention
The invention relates to a process for the manufacture of stable polyol-filler dispersions. More particularly, this invention relates to polyol-filler dispersions wherein fillers, preferably inorganic fillers, are crushed to particle sizes or less than 7 microns employing high localized energies in situ with polyols.
2. Prior Art
The manufacture of dispersions of fillers in organic polymers and hydroxyl group containing polyethers is known. For this purpose, aqueous polymer dispersions are generally mixed with polyethers and the water is subsequently removed. It was also suggested to produce graft polymers by in situ polymerization of ethylenically unsaturated monomers in possibly ethylenically unsaturated polyethers and to use the obtained product for the manufacture of polyurethanes.
If inorganic fillers are used for the manufacture of polyurethanes, these are normally incorporated in the polyols immediately prior to processing. It has also been attempted to disperse inorganic materials in polyethers. In most cases, such dispersions have very high viscosities which make processing considerably more difficult or even impossible. Another advantage is that the inorganic fillers, due to their higher specific weight, will sediment more quickly than organic polymers.
The purpose of this invention was the manufacture of storage-stable, non-sedimenting dispersions of fillers in polyols which, with a solids content of 10 percent by weight based on the total weight, have a viscosity of less than 2500 centipoises at 25.degree. C. and with solids contents of 20 percent by weight, have viscosities of less than 5000 centipoises at 25.degree. C.
It was found that storage-stable dispersions with the desired properties are obtained if the filler materials are crushed in situ in the polyols.
The object of this invention is therefore a process for the manufacture of stable filler polyol dispersions wherein the fillers are crushed with high localized energy densities to a particle size of less than 7 microns in situ in the polyols with the result that the filler particles are comminuted and thus simultaneously dispersed to form a stable dispersion.